The present invention relates to a method for the no-transmitter speed determination of an asynchronous machine, specifically for industrial trucks.
An industrial truck with a direct-current motor of a series circuit design without additional sensors for speed detection is known from DE 4042041 A1, the entire contents of which is incorporated hereby in reference in its entirety.
Asynchronous or synchronous motors stand out because of their no-maintenance and rugged technical equipment over direct-current motors. Moreover, asynchronous machines enjoy a comparative simple regulation.
WO 02/06076 A2, the entire contents of which is incorporated hereby in reference in its entirety, has made known a method for a sensorless drive regulation of an electric vehicle in which the stator current is determined depending on the actual values detected for a flux concatenation, the torque, and the conductor currents measured. For a determination of flux concatenation, a motor model is used which determines the speed and torque.
A tutorial by Joachim Holtz entitled “Sensorless Speed and Position Control of Induction Motors”, the entire contents of which is incorporated hereby in reference in its entirety, has become known from the meeting volume of the 27th Annual Conference of the IEEE Industrial Electronic Society, IECON, held in Denver, Colo., from Nov. 27 to Dec. 2, 2001. The tutorial presents a series of models which allow to calculate speeds without any speed detection. In particular, a difference is made between fed-back and non-fed-back observers for the magnetic flux.
It is the object of the invention to provide a regulation for an asynchronous machine that dispenses with using a speed sensor or incremental transmitter while permitting a rugged and simple regulation.